A Non-Flammable Electrolyte for Lithium-Ion Batteries Containing Lithium Difluoro(oxalato)borate, Propylene Carbonate and Tris(2,2,2-Trifluoroethyl)Phosphate

Lithium difluoro(oxalato)borate in the mixture of propylene carbonate and tris(2,2,2-trifluoroethyl)phosphate is introduced as a safe electrolyte for lithium-ion batteries. And fluoroethylene carbonate additive is used in this electrolyte to improve the compatibility with the graphite anode. It is found that 25 wt% tris(2,2,2-trifluoroethyl)phosphate endows this electrolyte with non-flammable characteristic and good wettability to separator and electrodes. This safe electrolyte can well support graphite/LiNi0.5Co0.2Mn0.3O2 full cells. Its cycle performances at room temperature and elevated temperature (60 °C) surpass those of a commercial electrolyte. And its rate performance at room temperature is also comparable to that of the commercial electrolyte. These results indicate that such a safe electrolyte shows a great potential for practical application.